A tank of motor vehicles contains a fuel delivery unit which essentially comprises a reservoir (splash pot), a fuel pump which is arranged therein and delivers fuel from there to the combustion engine, a further pump for filling the reservoir, and various lines. The reservoir, which is of cylindrical design (large height in relation to the base surface), ensures, by means of its limited volume, that the fuel pump is able constantly to take in fuel even in the case of prolonged accelerations in the plane of the road.
The further pump mentioned above can be a separate suction jet pump. Its driving jet can be fed by the return flow from an injection system or by the outward flow from the fuel pump.
It is also known to use a two-stage, motor-driven fuel pump whose first stage (preliminary stage) takes in fuel from the fuel tank and delivers it via a rising pipe into the reservoir and whose second stage (main stage) then delivers the fuel to the combustion engine. In a variant thereto, the preliminary stage draws the fuel out of the reservoir and uses it, on the one hand, to feed the suction jet pump to refill the reservoir and, on the other hand, to feed an outward flow to the second pump stage.
The outlet opening of such a preliminary stage is situated laterally in the lower region of a pump housing. If the latter is inserted into the reservoir, the abovementioned mouth lying only slightly above the bottom of the relatively narrow and high reservoir, there is not a great deal of space between the housing wall and the reservoir wall. It is therefore very difficult to connect an outward-flow line or rising line with the pump installed. The finished connection itself also has to manage with little space. Although it would be conceivable to provide a rising line fastened to the pump housing or integrated into the reservoir, this contradicts the requirement of being able freely to use standardized mass-produced pumps having uniform external dimensions.